Electrodes are often used to stimulate contraction of the heart. For example, when a patient's heart is functioning with an abnormal rhythm, electrical energy may be applied to the heart via the electrodes to return the heart to a normal rhythm. In some cases this procedure may be an isolated event while in other cases a more frequent, regular, or even continuous process is used. In these cases electrodes may be incorporated into a lead that is used with a pacemaker, defibrillator, or other electrical stimulation device such that pacing pulses may be delivered, for example, to an atrium or ventricle of a heart. The system including the electrical stimulation device and the lead may be implantable and, thus, used over long periods of time.
In general, a lead includes a pair of electrodes disposed at a distal end of the lead which may be positioned in the right ventricle or the right atrium of the heart. The proximal end of the lead may be coupled to a defibrillator or a pacemaker and conductors may deliver electrical impulses along the length of the lead to the electrode thereby delivering pacing pulses to the heart.
There are at least two conventional types of leads. The first type of leads is referred to as an active electrical lead with an active mechanism at the distal end. The second type of leads is referred to as a passive electrical lead with a passive mechanism at the distal end.
The distal end of a typical active electrical lead may include a helix type fixation mechanism designed to be actuated and axially extend and/or rotate out of a tip portion of the lead to engage or embed into the endocardium. The distal end of a typical passive electrical lead may include an anchor type fixation mechanism designed to anchor the distal end in the heart. The fixation mechanism for a passive lead, for example, may include one or more radially spaced tines that secure the distal end in the heart.
The proximal end of pacemaker and defibrillator leads are commonly designed and manufactured to a standard such as YY/T 0491-2004//ISO 5841-3, 2000. The standard is applicable to both active and passive pacemaker or defibrillator leads. Within that standard, medical device implant companies commonly have their own unique designs. Among the technologies used to meet the standard, are laser welding and metal crimping resulting in highly reliable pacemaker and defibrillator lead joint connections.
The design of defibrillator and pacemaker leads has evolved over time. Over time and at present, the proximal end of an active electrical lead and the proximal end of a passive electrical lead are generally designed differently due to their functional differences. That is, the proximal end of an active lead may be designed to actuate and/or control the distal active mechanism, while the proximal end of a passive lead may not include such actuation and/or control features. System designs and assembly processes of the passive and active electrical leads are, thus, different. As a result, the overall cost of having significant different system designs and assembly processes is relatively high and a system having common features or similar or exchangeable components between an active electrical lead and a passive electrical lead may be less expensive and more attractive to consumers.